[PATCH] D109821: [ScalarEvolution][LoopIdiom] Infer loop max trip count from array accesses

[Liren.Peng via Phabricator via llvm-commits]

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Data references in a loop should not access elements over the
statically allocated size. So we can infer a loop max trip count
from this undefined behavior.
And if we have got a certain loop bound which is small enough,
do not go through loop idiom pass because giving a libcall may
break down performance.
we can enable Loop Idiom regardless of loop trip count  by passing
“-use-lir-loop-max-tripcount=0” in command line.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109821

Files:
  llvm/include/llvm/Analysis/ScalarEvolution.h
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
  llvm/test/Analysis/GlobalsModRef/memset-escape.ll
  llvm/test/Transforms/InstMerge/st_sink_bugfix_22613.ll
  llvm/test/Transforms/LoopIdiom/memset_noidiom.ll
  llvm/test/Transforms/LoopIdiom/pr28196.ll
  llvm/test/Transforms/LoopIdiom/reuse-cast.ll

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